1. Field of the Invention
The present invention relates to a control method of a cooling water pump of a fuel cell vehicle in which the on/off and revolutions per minute (RPM) of the cooling water pump are controlled more accurately based on the stack temperature and required output of the fuel cell vehicle to prevent flooding of the fuel cell vehicle and to improve acceleration response of a stack and cell temperature uniformity.
2. Description of the Related Art
A fuel cell is a device that generates electricity by electrochemical reactions between hydrogen and oxygen, and the fuel cell has high efficiency and minimal discharge of contaminants, as compared to conventional power generation methods. In general, in such a fuel cell, hydrogen is supplied to an anode, oxide gas including oxygen is supplied to a cathode, and electrons move by reactions through an electrolyte membrane to generate electricity. Particularly, heat of reaction is generated from the fuel cell due to such exothermic reactions.
The temperature of a fuel cell module is increased by a heating value generated through such a method and performance of the fuel cell may be lowered due to deterioration of unit cells of the fuel cell. Particularly, among fuel cells, a proton exchange membrane (PEM) type fuel cell applied to middle and small capacities has an operation temperature of about 60° C. to 80° C., performs cooling and heat discharge to maintain efficiency and stability of the fuel cell, and requires a cooling device to adjust temperature for recovering excessive heat or supplying heat during starting. Such a fuel cell cooling device may include an air cooling device or a water cooling device configured to supply cooling water to dissipate heat generated from a fuel cell module.
However, in this case, heat of reaction generated from the fuel cell module may not be actively adjusted and it may be difficult for such a fuel cell cooling device to effectively cope with temperature change caused by variation of load of the fuel cell. Further, for a system that includes a heat exchanger to cool cooling water, when performance of the heat exchanger is reduced, it may be difficult to stably drive the cooling system. Therefore, to stably drive a fuel cell, a cooling device which may effectively cope with temperature change of the fuel cell module is required.
Various methods for effectively cooling a fuel cell vehicle have been developed. For example, a method in the prior art provides a method which elongates the limitation current arrival time of a vehicle to improve output stability of a stack when the temperature of the stack is increased, and improves durability of an ion filter, into which cooling water of a high temperature is introduced.
However, even using the above method, flooding due to inefficiency of the cooling system of the fuel cell vehicle may still occur and, in a low temperature state of the fuel cell vehicle, the temperature of the fuel cell stack may not be determined accurately and thus efficiency in control of the fuel cell cooling system may decrease.
The above description has been provided to aid in understanding of the background of the present invention and should not be interpreted as conventional technology known to those skilled in the art.